+R wall
Figure 1 Photographs of shellside hydrocarbon fouling build-up on heat transfer tubes
As heat release progresses, the shellside heat transfer rate declines:
Overall heat transfer rate clean - U clean =
1
1
OD
+
+ R wall
H shellside
ID * H tubeside
Heat release curve along with water plus hydrocarbon condensate formation example (as follows):
Fouled heat transfer rate - U fouled =
1
1 U clean
+ OAFF
The tubeside heat transfer rate is generally a straight- forward calculation of forced convection in the turbulent flow:
Design or working heat transfer rate - U working = Heat released Area * LMTD
10,000 12,000 14,000 18,000 16,000 20,000
100 120 140 180 160 200
Hotside
Coldside PPH HC liquid (RHS)
PPH Water (RHS)
PPH Non condensible gas (RHS)
0 6,000 4,000 2,000 8,000
0 60 40 20 80
0
2,000,000
4,000,000
6,000,000
8,000,000 10,000,000 12,000,000 14,000,000 16,000,000 18,000,000
Heat release (Btu/hr)
Figure 2 Heat release 30,000 pph mass flow rate (at 200 mm Hg abs for illustration only)
60
PTQ Q1 2023
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